JP2008003452A - Lens barrel and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a lens barrel having a constitution that uses a cam barrel for making a lens group move, and made small-sized in cross-sectional area, in a direction orthogonal to the optical axis. <P>SOLUTION: The lens barrel has the lens group which moves in the optical axis direction; a plurality of guide parts which guide the lens group in the optical axis direction; and a cam member which has a cam part that engages with the lens group, and the cam member is arranged, held in between the plurality of guide parts. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lens barrel configured to move a lens group in an optical axis direction, and an imaging apparatus including the lens barrel.

  2. Description of the Related Art Conventionally, cameras equipped with a variable focal length photographing lens (hereinafter also referred to as a zoom lens) are commercially available. The zoom lens is configured to change the focal length (zooming) by moving at least two lens groups constituting the optical system to desired positions along the optical axis and changing the distance therebetween. .

  There are roughly two types of methods for moving the lens group along the optical axis. The lens frame is guided in a straight line, and the lens frame is moved in a straight line by rotating the cam barrel, and the axis is substantially parallel to the optical axis. This is used as a guide shaft for linear guide, and a sleeve through which the guide shaft passes is formed in the lens frame, and the lens frame is slid directly along the guide shaft using a motor and a lead screw to move straight. There is.

On the other hand, a camera having a so-called bending optical system in which a reflecting surface is disposed in an optical system and an optical axis is bent is known. At the time of zooming of the bending optical system, there is a type in which a cam cylinder is rotated by a motor to move a lens group, and a guide shaft is used as a rectilinear guide inside the cam cylinder (for example, see Patent Document 1).
JP 11-258678 A

  In a lens barrel configured to move a lens group using a cam cylinder, a plurality of lens groups can be moved by drawing a desired movement curve with a single motor, for example. Like the lens barrel, a guide shaft is arranged outside the effective diameter of the moving lens group, and a cylindrical cam cylinder is arranged outside the guide shaft, and the direction orthogonal to the optical axis of the lens barrel There is a problem that the cross-sectional area becomes large.

  In view of the above problems, an object of the present invention is to obtain a lens barrel having a small cross-sectional area in a direction orthogonal to the optical axis, using a cam cylinder for moving a lens group, and including the lens barrel. Therefore, it is an object to obtain a compact imaging device.

  The above object is achieved by the invention described below.

  1. A plurality of lens groups that move in different amounts in the optical axis direction, a plurality of guide portions that guide the plurality of lens groups in the optical axis direction, and a cam portion that is disposed between the plurality of guide portions. And a lens barrel.

  2. Engage with a plurality of lens groups for guiding subject light, a plurality of guide members for guiding at least two moving lens groups of the plurality of lens groups in the optical axis direction, and at least two moving lens groups And a cam member having a cam portion, wherein the cam member is disposed between the plurality of guide members.

  3. 3. The lens barrel according to 2, wherein the cam member is formed in a cylindrical shape and is disposed between two moving lens groups.

  4). 4. The lens barrel according to 2 or 3, wherein at least one cam portion formed on the cam member is formed in a stepped shape.

  5. The lens barrel according to any one of claims 1 to 4, wherein the lens group engaged with the cam member is biased in the direction of the cam member.

  An imaging apparatus comprising the lens barrel according to any one of 6.1 to 5.

  According to the present invention, it is possible to obtain a lens barrel having a small cross-sectional area in a direction orthogonal to the optical axis even with a configuration using a cam cylinder to move the lens group. It is possible to obtain an image pickup apparatus.

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited thereto.

  FIG. 1 is a diagram illustrating an example of an internal arrangement of main constituent units of a camera 100 that is an example of an imaging apparatus including a lens barrel according to the present embodiment. FIG. 3 is a perspective view of the camera 100 as viewed from the subject side.

  As shown in the figure, in the camera 100, a lens barrel 50 according to the present invention that includes a foldable imaging optical system capable of zooming is arranged vertically on the right side as shown in the figure, and an opening 51 takes in a subject light flux. Has been placed. The opening 51 is provided with a lens barrier (not shown) that is in an open state that exposes the opening 51 and a closed state that covers the opening 51.

  Reference numeral 52 denotes a flash light emission window. Reference numeral 53 denotes a flash unit including a reflector, a xenon tube, other main capacitors, a circuit board, and the like disposed behind the flash light emission window. Reference numeral 54 denotes a card-type image recording memory. A battery 55 supplies power to each part of the camera. The image recording memory 54 and the battery 55 can be inserted and removed from a lid (not shown).

  A release button 56 is disposed on the upper surface of the camera. When the first button is pushed, a shooting preparation operation of the camera, that is, a focusing operation and a photometric operation are performed, and a shooting exposure operation is performed by pushing the second button. A main switch 57 is a switch for switching the camera between an operating state and a non-operating state. When switched to the operating state by the main switch 57, the lens barrier (not shown) is opened and the operation of each part is started. When the main switch 57 is switched to the non-operating state, the lens barrier (not shown) is closed and ends the operation of each unit.

  On the back side of the camera, an image display unit 58 configured by an LCD, an organic EL, or the like and displaying an image and other character information is disposed. Although not shown, a zoom button for zooming up and down, a playback button for playing back a captured image, a menu button for displaying various menus on the image display unit 58, and a desired function are selected from the display. An operation member such as a selection button is arranged.

  Although not shown, each part is connected between these main constituent units and a circuit board on which various electronic components are mounted is arranged to drive and control each main constituent unit. Yes. Similarly, although not shown, an external input / output terminal, a strap attaching portion, a tripod seat, and the like are provided.

  FIG. 2 is a cross-sectional view showing a foldable imaging optical system capable of zooming, which is included in the lens barrel 50 according to the present embodiment. This figure is a cross-sectional view cut along a plane including two optical axes, an optical axis OA before bending and an optical axis OB after bending. FIG. 4A shows the position of each lens group in the wide state, and FIG. 6B shows the position of each lens group in the tele state.

  In the figure, reference numeral 1 denotes a first lens group. The first lens group 1 includes a lens 11 arranged with an optical axis OA and facing a subject, and a prism 12 that is a reflecting member that bends the optical axis OA in a substantially right angle direction. And a lens 13 arranged with the optical axis OB bent by the prism 12 as an optical axis. The first lens group 1 is a fixed lens group that does not move.

  Reference numeral 2 denotes a second lens group. The second lens group 2 is a lens group that moves in the direction of the optical axis OB as shown together with a lens frame (not shown) during zooming (hereinafter also referred to as zooming).

  Reference numeral 3 denotes a third lens group. The third lens group 3 is a lens group that does not move in the direction of the optical axis OB. In addition, although S is a diaphragm shutter operation surface, it does not need to be.

  Reference numeral 4 denotes a fourth lens group. The fourth lens group 4 is a lens group that moves in the optical axis OB direction together with a lens frame (not shown) at the time of zooming and focus adjustment (hereinafter also referred to as focusing).

  Reference numeral 5 denotes a fifth lens group. The fifth lens group 5 is a fixed lens group that does not move in the direction of the optical axis OB.

  Reference numeral 7 denotes an infrared light cut filter, and an optical low-pass filter is appropriately stacked as necessary.

  An imaging element (not shown) is disposed behind the infrared light cut filter 7. A CCD (Charge Coupled Device) type image sensor, a CMOS (Complementary Metal-Oxide Semiconductor) type image sensor, or the like is used as the imaging element.

  FIG. 3 is a plan view showing a schematic structure inside the lens barrel 50 according to the present embodiment. FIG. 2 schematically shows the schematic structure of the lens barrel 50 for easy understanding. In addition, in the figure shown below, in order to avoid duplication of description, it attaches | subjects and demonstrates the same code | symbol to the same function member.

  In the figure, reference numeral 2k denotes a second lens group lens frame that holds the second lens group 2. Reference numeral 4 k denotes a fourth lens group lens frame that holds the fourth lens group 4. Reference numerals 15 and 16 are guide axes, which are arranged substantially parallel to the optical axis OB.

  The second lens group lens frame 2k is integrally formed with a sleeve portion 2s through which the guide shaft 15 penetrates, and is integrally formed with a rotation locking portion 2m that engages with the guide shaft 16. Thereby, the second lens group 2 is movable in the direction of the optical axis OB.

  Similarly, a sleeve portion 4s through which the guide shaft 15 penetrates is integrally formed in the fourth lens group frame 4k, and a rotation locking portion 4m that engages with the guide shaft 16 is integrally formed. . Thereby, the fourth lens group 4 is movable in the direction of the optical axis OB.

  A cylindrical cam member 10 is disposed at a position between the second lens group lens frame 2k and the fourth lens group lens frame 4k. Reference numeral 20 denotes a stepping motor (hereinafter also referred to as a motor), and a gear 21 is assembled to the rotating shaft of the motor 20.

  The rotation of the gear 21 due to the rotation of the motor 20 is shown as a single gear in the figure, but is transmitted to the gear portion 10g formed on the cam member 10 via the reduction gear train 22 so that the cam member 10 is rotated. It has become.

  As shown in the figure, the cam member 10 has stepped cam surfaces C1, C2, and C3 having different heights at one circumferential end. In the figure, the protrusion 2t formed on the second lens group lens frame 2k is in contact with the cam surface C1. Further, a cam surface Cs, which is a gentle continuous inclined surface, is formed at the other circumferential end, and the protrusion 4t formed on the fourth lens group lens frame 4k is in contact with the cam surface Cs. ing. The second lens group frame 2k and the fourth lens group frame 4k are urged toward the cam member 10 by an urging member (not shown).

  The cam surface C1 formed on the cam member 10 is set to the wide position, C2 is set to the middle position, and C3 is set to the tele position. In the following description, the focal length setting of three points of wide, middle, and tele is described, but the focal length setting is not limited to three points.

  Thus, by driving the motor 20 and rotating the cam member 10, the second lens group frame 2k, that is, the second lens group 2, and the fourth lens group frame 4k, that is, the fourth lens group 4, have the optical axis OB. Can be moved in the direction.

  Although not shown, a photo interrupter for detecting the initial position of the fourth lens group frame 4k is arranged. The rotation direction and the rotation amount of the motor 20 are controlled on the basis of this initial position. The initial position detection of the lens group lens frame may be a photo reflector.

  FIG. 4 is an exploded perspective view schematically showing the main part of the lens barrel 50 according to the present embodiment. In the figure, the second lens group lens frame 2k, the fourth lens group lens frame 4k, the cam member 10, the motor 20, and the like are extracted, and the third lens group 3 which is a fixed lens group is omitted. FIG. 2 shows the wide state of FIG.

  As shown in the figure, the guide shaft 15 is fitted with a sleeve portion 2 s formed integrally with the second lens group frame 2 k that holds the second lens group 2, and the guide shaft 16 is rotated. The locking part 2m is engaged. Similarly, a sleeve portion 4 s formed integrally with a fourth lens group lens frame 4 k that holds the fourth lens group 4 is fitted to the guide shaft 15, and a rotation locking portion 4 m is fitted to the guide shaft 16. Are engaged.

  The cam member 10 is formed with stepped cam surfaces C1, C2, and C3 having different heights. In the state shown in the drawing, the protrusion 2t formed on the second lens group frame 2k abuts the cam surface C1, The projection 4t formed on the fourth lens group frame 4k is in contact with the cam surface Cs.

  The lens driving device 50 according to the present embodiment performs the following operation as the motor 20 rotates.

  FIG. 5 is a movement diagram of the second lens group 2 and the fourth lens group 4 of the lens barrel 50 according to the present embodiment.

  As shown in the figure, the first, third, and fifth lens groups (indicated by 1, 3, and 5 in the figure, respectively) do not move, and the second lens group 2 (indicated by 2 in the figure) has the above-mentioned stepped shape. A wide position corresponding to the cam surface C1, a middle position corresponding to the cam surface C2, and a tele position corresponding to the cam surface C3 are moved in order to approach the third lens group 3 step by step.

  On the other hand, the fourth lens group 4 (shown as 4 in the figure) moves so as to continuously approach the third lens group along the above-described cam surface Cs, and the position of the second lens group 2 does not change. The focusing at each focal length position is performed by the movement of the fourth lens group 4 in the flat areas of the cam surfaces C1, C2, and C3 indicated by the one-dot chain line. In the drawing, Fw represents the focusing movement amount of the fourth lens group 4 at the wide position, Fm represents the focusing movement amount of the fourth lens group 4 at the middle position, and Ft represents the fourth lens at the tele position. The focusing movement amount of group 4 is shown.

  As described above, by arranging the cam member 10 so as to be sandwiched between the guide shafts 15 and 16, the diameter of the cam member can be reduced, and a lens barrel having a small cross-sectional area in the direction perpendicular to the optical axis can be obtained. Is possible. Furthermore, one cam surface is formed in a step shape, and the other lens group is moved in an area where the position of one lens group does not change (flat area). Focusing at the focal length position is possible, and a small and low-cost lens barrel can be obtained. Furthermore, by providing this small and low-cost lens barrel, a small and low-cost imaging device can be obtained.

  In the above embodiment, the protrusions 2t and 4t are formed on the second lens group frame 2k and the fourth lens group frame 4k, respectively, so that the second lens group frame 2k and the fourth lens group frame 4k are formed. However, the present invention is not limited to this, and cam shapes are respectively formed on the opposing surface sides of the second lens group frame 2k and the fourth lens group frame 4k. A ring member having a projecting portion that contacts each cam shape may be arranged, and the ring member may be rotated by the motor 20.

  Further, although the above embodiment has been described using the lens barrel of the bending optical system having the reflecting surface in the optical system, it can also be applied to the lens barrel of the optical system having no ordinary reflecting surface.

It is a figure which shows an example of the internal arrangement | positioning of the main structural unit of the camera which is an example of the imaging device provided with the lens barrel which concerns on this Embodiment. 1 is a cross-sectional view illustrating a foldable imaging optical system that is variable in magnification and is contained in a lens barrel according to the present embodiment. It is a top view which shows schematic structure inside the lens barrel which concerns on this Embodiment. It is the disassembled perspective view which showed typically the principal part of the lens barrel which concerns on this Embodiment. It is a movement diagram of the 2nd lens group and the 4th lens group of the lens barrel concerning this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st lens group 2 2nd lens group 2k 2nd lens group frame 3 3rd lens group 4 4th lens group 4k 4th lens group frame 5 5th lens group 7 Optical filter 8 Imaging element 10 Cam member 15, 16 Guide shaft 20 Stepping motor 21 Gear 22 Reduction gear train 50 Lens barrel 100 Camera

Claims (6)

A plurality of lens groups that move in different amounts in the optical axis direction, a plurality of guide portions that guide the plurality of lens groups in the optical axis direction, and a cam portion that is disposed between the plurality of guide portions. And a lens barrel. Engage with a plurality of lens groups for guiding subject light, a plurality of guide members for guiding at least two moving lens groups of the plurality of lens groups in the optical axis direction, and at least two moving lens groups A cam member having a cam portion to be
The lens barrel, wherein the cam member is disposed between the plurality of guide members. The lens barrel according to claim 2, wherein the cam member is formed in a cylindrical shape and is disposed between two moving lens groups. The lens barrel according to claim 2 or 3, wherein at least one cam portion formed on the cam member is formed in a stepped shape. The lens barrel according to claim 1, wherein the lens group engaged with the cam member is biased in the direction of the cam member. An imaging apparatus comprising the lens barrel according to claim 1.

Images